China's bamboo dragonfly and Italian Leonardo da Vinci's helicopter sketches provided inspiration for the invention of modern helicopters and pointed out the correct thinking direction. They are recognized as the starting point of the history of helicopter development. Bamboo dragonfly, also known as flying snail and "China gyro", is a strange invention of our ancestors. Some people think that there were bamboo dragonflies in China in 400 BC, and another conservative estimate is that it was in the Ming Dynasty (AD 1400). This kind of folk toy called bamboo dragonfly has been passed down to this day. Detailed records of bamboo dragonflies can be found in the Jin Dynasty (AD 265-420'). Ge Hong wrote Bao Puzi. It uses the aerodynamic force of propeller to achieve vertical lift, demonstrating the basic working principle of modern helicopter rotor. Although modern helicopters are thousands of times more complicated than bamboo dragonflies, their flight principles are similar to those of bamboo dragonflies. The rotor of modern helicopter is like the blade of bamboo dragonfly, the rotor shaft is like the thin bamboo pole of bamboo dragonfly, and the engine that drives the rotor is like the hand that rubs the bamboo pole hard. The leaves of bamboo dragonfly are blunt at the front and sharp at the back, and the upper surface is relatively round and the lower surface is relatively straight. When the airflow passes through the upper surface of the circular arch, the speed is fast and the pressure is small; When the airflow passes through the flat lower surface, its velocity is slow and its pressure is high. Therefore, a pressure difference is formed between the upper surface and the lower surface, and an upward lift force is generated. When the lift is greater than its own weight, the bamboo dragonfly will fly. Helicopter rotors generate lift for the same reason as bamboo dragonflies. This kind of toy was introduced to Europe in the14th century, which brought the creation of China people. Europeans study and develop it as an airplane. George, the "father of British Airways"? Kelly (1773- 1857) once made several bamboo dragonflies, which were driven by clockwork and flew at a height of 27M. Encyclopedia Britannica records that this kind of "helicopter toy" called "China Gyro" was built in the middle of15th century, that is, in Da? Before Finch drew the helicopter design with propeller rotor, it had been introduced to Europe. The ninth volume of The Concise Encyclopedia of Britain wrote: "Helicopter is one of the earliest flying ideas of human beings. For many years, people have always thought that Dada first put forward this idea. Finch, but now we all know that China made helicopter toys before the Europeans in the Middle Ages. /kloc-At the end of 0/9, Dada was found in Milan Library, Italy. An imaginary helicopter map drawn by Finch in 1475. This is a huge spiral body, made of pulped linen, which looks like a huge screw. It is powered by a spring, and when it reaches a certain speed, it will take the body into the air. The driver stands on the chassis and pulls the wire rope to change the flight direction. Westerners say this is the earliest blueprint for helicopter design. The early 20th century was the exploration period of helicopter development, and many experimental models came out one after another. It has accumulated valuable experience for the development of helicopters and made remarkable progress. Many testing machines have achieved short-time vertical lift-off and short-distance flight, but there were still two main obstacles at that time: the gestation process of helicopters was difficult, and its development was hindered by three technical difficulties. The breeding process of helicopter is difficult, and three technical difficulties hinder its development. One is the engine with high power-to-weight ratio, the other is how to balance the torque generated when the rotor rotates, and the third is how to realize flight control. First, the engine with high power-to-weight ratio was too low at that time, and the helicopter was particularly sensitive to this index; The second is how to balance the torque produced by rotor rotation and the reaction torque produced by rotor rotation. The third is how to realize flight control. At that time, the rotor technology was too primitive to control the helicopter effectively, and the vibration was very serious. The appearance of the steam engine once brought a glimmer of hope to the helicopter, but it was quickly denied. The appearance of internal combustion engine makes the engine meet the requirements of helicopter. The appearance of the steam engine once brought a glimmer of hope to the helicopter, but it was quickly denied. The appearance of internal combustion engine, especially the development of aircraft industry, has rapidly improved the performance of aero-engines and provided important conditions for the success of helicopters. Only in this way can the engine meet the requirements of the helicopter. In order to overcome the torque problem, most of the early helicopter schemes are multi-rotors, and the balance problem is solved by the rotation of the rotors. The diversity of schemes shows the immaturity of technology in the exploration stage. After years of practice, only tandem type and * * * axis twin-rotor type have survived and are still in use today. The twin-propeller series scheme did not continue in the helicopter family, but it was inherited and developed in the tilt rotor/wing vertical take-off and landing aircraft. Yulyev, a Russian, found another shortcut, put forward a design scheme of balancing rotor reaction torque with tail rotor, and made a testing machine at 19 12. This single-rotor helicopter with tail rotor has become the most popular form so far, accounting for more than 95% of the total number of helicopters in the world. The most common method is to adopt the layout of single rotor+tail rotor, including tandem twin rotors, transverse twin rotors and * * * axis twin rotors. The most common way to overcome the torque problem is to adopt the layout of single rotor+tail rotor, including tandem double rotor, transverse double rotor and * * * axis double rotor. As for flight control, the usual practice is to set flapping hinges on the rotor hub and pitch control mechanism of rotor blades. As for flight control, the usual practice is to set flapping hinges on the rotor hub and pitch control mechanism of rotor blades. In this process, the first breakthrough of rotor technology, Spanish Juan? Ciervao contributed a lot. He first invented the rotorcraft, replacing the wing with a rotating rotor, in order to create a "stall-free" aircraft to solve the safety problem of fixed-wing aircraft. According to the invention, flapping hinges and periodic pitching changes are installed on the rotor, so that the rotor can generate stable lift in vertical flight and forward flight, and can also generate pitching and rolling control moments. It has had an important impact on the maturity and development of helicopter technology and provided another important condition for the birth of helicopters. 1August 907, Frenchman Paul? Kearney developed a full-scale manned helicopter, which was successfully tested in June of the same year 165438+ 10/3. This helicopter is called "the first human helicopter". The helicopter named "Flying Bicycle" not only left the ground 0.3 meters by its own power, but also flew vertically for 20 seconds, realizing free flight. The helicopter developed by paul cornu has two rotors, the main structure is a V-shaped steel pipe, and the fuselage is composed of a V-shaped steel pipe and six star-shaped blades, which are reinforced with steel cables to increase the rigidity of the frame structure. The 24 horsepower Antainette engine and the operator seat are installed in the middle of the V-shaped frame. The fuselage is 6.20 meters long and weighs 260 kilograms. A pair of rotors with a diameter of 6 meters are installed at both ends of the V-shaped frame, and each rotor has two blades. 1933, fokker of fokker company in Germany? Wolf designed a helicopter FW-6 1 with an airplane fuselage and two rows of rotors, which is the first helicopter with mature technology in the world. 1936, Fokker publicly demonstrated the FW-6 1 helicopter which was improved in many aspects on the early helicopter. 1 year later, this helicopter created many world records. This is a large twin-rotor tandem helicopter with a fuselage similar to that of a fixed-wing aircraft, but without a fixed wing. Its two rotors are supported on the upper right and left by two groups of thick metal frames respectively, and the two rotors are horizontally installed on the top of the bracket. The plane shape of the blade is sharp, and it is connected with the hub through flapping hinge and dragging hinge. The automatic tilter is used to tilt the rotor rotation plane for longitudinal control, and the yaw control is realized by tilting the two rotors in different directions. The total pitch of rotor blades is fixed, and the rotor tension is changed by changing the rotor speed. Use rudder and horizontal tail to increase stability. FW6 1 Rotor hub is equipped with a periodic pitch changing device, which can change the blade pitch during the rotor rotation. There is also a pitch control lever, which can change the inclination of the rotor surface and realize the flight direction control. FW6 1 ensures its maneuvering flight through this set of periodic range-changing devices and joysticks. The diameter of the rotor of the plane is 7 meters. The power unit is a piston engine with power 140 horsepower. This is the first helicopter with normal maneuverability in the world. The speed of the aircraft is 100 ~ 120km, the range is 200km, and the takeoff weight is 953kg. 1938, a young German girl Hannah? Reich flew a FW-6 1 in Berlin Stadium and performed a perfect flight performance, flying forward, flying backward, hovering and turning, which showed people the unique charm of the helicopter for the first time. This helicopter is considered by the helicopter industry to be the first successful helicopter in the world. 19 19, Sicorschi moved to the United States. 1928 became an American citizen, and Sikorsky Aircraft Company was established the following year. Sikorsky has returned to the development of helicopters. In less than three years, he solved the biggest problem of helicopters-the problem of helicopters spinning in the air. He skillfully installed a pair of small rotors-tail rotors with vertical rotation and reaction at the tail, and finally made the helicopter fly into the sky. 1September, 939 14, Sicorschi lifted a helicopter into the air, about two or three meters high, suspended smoothly for 10 second, and then landed lightly on the ground. This is a brand-new chapter in aviation history. He successfully launched the first real helicopter in the world-VS-300. After repeated flight tests, VS-300 has good maneuverability and the basic characteristics of modern helicopters. 1940 At the end of the year, the U.S. Army decided to purchase the improved VS-3 16 of VS-300 in large quantities, and the Army number was R-4. R-4 is a biplane with main wing diameter 1 1.58 m and maximum weight 1 152 kg. It uses 185 horsepower piston engine, cruise speed 109 km/h, range of 320 km, and ceiling of 65438. Can take off and land vertically, hover, fly forward, fly backward, fly sideways, spin down without power, etc. , fully has the flight characteristics of modern helicopters. The first R-4 was delivered to the US Army in May 1942. Later, Sicorschi developed R-5 and R-6 helicopters based on R-4, which improved their performance. By the end of 1930s, France, Germany, the United States, and the Soviet Union all had successful helicopter test flights, and they quickly improved to practical level. The military demand of World War II accelerated this process, which prompted the development of helicopters to enter the practical period from the exploration period, and helicopters began to be put into production lines. By the end of World War II, German factories had produced more than 30 helicopters, and the United States delivered more than 400 Israeli, R5 and R6 helicopters. Shortly after the appearance of R-4, in March of 1946, the American Bell 47 helicopter obtained the first airworthiness license for commercial helicopters. Before the mid-1950s, the power plant of helicopter was in the period of piston engine, and then it entered the period of jet turbine shaft. The rotor material structure technology has also gone through several stages; From 1940s to 1950s, it was a mixed structure of metal wooden wings, from the mid-1950s to the mid-1960s, it was a metal structure, from the mid-1960s to the mid-1970s, it was a glass fiber structure, and it developed into a new composite structure after the mid-1970s. From the 1940s to the mid-1950s, it was the first stage of the development of practical helicopters. Typical aircraft types in this period are: S-5 1, S-55/H- 19, Bell 47; Soviet Mi -4 and Ka-18; Bristol, England-171; Czech HC-2 and so on. Helicopters in this period can be called the first generation helicopters. Bell 47 is a single-engine light helicopter developed by American Bell Helicopter Company. The development work started at 194 1, and the testing machine bell 30 started at 1943. It was renamed as Bell 47, 1945, and obtained the airworthiness certificate of CAA on March 8, 2006. The machine is a seesaw rotor, single rotor and tail rotor layout, with two blades. There is a stabilizer bar under the rotor, which is at right angles to the blades. Ordinary automatic turning machine can operate the change of total pitch and periodic pitch. All-metal tail rotor with two blades at the back of the tail beam. Ka-18 is a single-engine dual-rotor light multi-purpose helicopter designed by Kamov Design Bureau of the Soviet Union. /kloc-0 made its first flight in mid-1957, and put it into mass production shortly thereafter. Two pairs of three-blade axial flow rotors with opposite rotating directions are adopted, and the blades are made of wood. Install 1 9-cylinder star piston engine with 275 horsepower. The fuselage is welded steel pipe structure, light metal skin and hard shell tail beam. The cockpit can accommodate 1 pilot and 3 passengers. With four-wheel landing gear, the front landing gear wheel can rotate freely. The helicopter at this stage has the following characteristics: the power source is a piston engine, with low power, low specific power (about 1.3 kW/kg) and low specific capacity (about 247.5 kg/m3). The life of rotor blades with wood or steel-wood mixed structure is short, about 600 flight hours. The airfoil of the blade is symmetrical, the tip is rectangular, and the aerodynamic efficiency is low. The rotor lift-drag ratio is about 6.8, and the rotor efficiency is usually 0.6. The machine body structure adopts all-metal frame type, and the empty weight accounts for a large proportion of the total weight, about 0.65. There is no necessary navigation equipment, only a single-function visual flight instrument, and the communication equipment is electronic tube equipment. Poor dynamic performance, low maximum flight speed (about 200 km/h), vibration level of about 0.25g, noise level of about 1 10 dB, and poor ride comfort. The mid-1950s to the late 1960s was the second stage of the development of practical helicopters. Typical aircraft types at this stage are: S-6 1 from the United States, Bell 209/AH- 1, Bell 204/UH- 1, Mi -6, Mi -8, Mi -24 from the Soviet Union, and SA32 1 "Super. During this period, special armed helicopters began to appear, such as AH- 1, Mi -24 and so on. These helicopters are called the second generation helicopters. The helicopter at this stage has the following characteristics: the first generation turboshaft engine is used as the power source. The power generated by turboshaft engine is much higher than that of piston engine, which greatly improves the performance of helicopter. The specific power of the first generation turboshaft engine is about 3.62 kW/kg, and the specific capacity is about 294.9 kW/m3. Helicopter rotor blades have developed from wood and steel-wood mixed structure to all-metal blades, and their service life has reached 1200 flight hours. The blade profile is asymmetric, the blade tip is simply sharpened and swept back, and the aerodynamic efficiency is improved. The lift-drag ratio of the rotor reaches 7.3, and the rotor efficiency is improved to 0.6. The machine body structure is all-metal thin-walled structure, and the ratio of empty weight to total weight is reduced to about 0.5. Energy-absorbing landing gear and damping seat are adopted. The fuselage shape began to streamline to reduce aerodynamic drag. The helicopter cockpit began to be arranged in series, which made the fuselage narrow. The performance is obviously improved, the maximum flight speed reaches 200 ~ 250km/h, the vibration level is reduced to about 0. 15g, and the noise level is 100 dB, which improves the ride comfort. The 1970s and 1980s were the third stage of helicopter development, with typical models as follows: American S-70/UH-60 Black Hawk, S-76, AH-64 Apache, Soviet Ka -50 and Mi -28, French SA365 Dolphin and Italian A65438+. At this stage, specialized civil helicopters appeared. In order to deeply study the aerodynamics of helicopters, special helicopter research machines (such as S-72 and Bell 533) were designed and manufactured. Countries compete to develop special armed helicopters, which promotes the development of helicopter technology. At this stage, the helicopter has the following characteristics: the turboshaft engine developed to the second generation and changed to the free turboshaft structure, so it has better speed control characteristics and improved starting performance, but its acceleration performance is not as good as that of the fixed-axis structure. The weight and volume of the engine are reduced, and the life and reliability are improved. The fuel consumption of a general engine is 0.36kg/kWh, which is similar to that of a piston engine. Rotor blades are made of composite materials, and their service life is much longer than that of metal blades, reaching about 3600 hours. The airfoil is no longer used for reference from fixed-wing aircraft, but is specially developed for helicopters, that is, the airfoil with two-dimensional curve change. The tip of the blade is parabolic and swept back. Elastic bearings are widely used in wheel hubs, some of which are hinged. Efficient and safe ducted tail rotor has been applied to tail rotor. The rotor lift-drag ratio is about 8.5, and the rotor efficiency is improved to about 0.7. The substructure of the airframe is also made of composite materials, and the ratio of composite materials to the total weight of the airframe is usually about 10%, and the ratio of empty weight to the total weight of the helicopter is generally 0.5. For military helicopters, especially armed helicopters, the requirements of bullet resistance and crash resistance are put forward. The US military put forward MIL-STD- 1290, which has become the design standard of military helicopters. In order to meet these standards, military helicopters adopt crew armor protection, and specially design crash-resistant landing gear, seat and fuel system. The electronic system has developed to a semi-integrated type. Helicopters use large-scale integrated circuit communication equipment, integrated autonomous navigation equipment, integrated instruments, electronic and mechanical hybrid control mechanisms, etc. The electronic equipment on the ship is connected through a bidirectional digital data bus, through which information can be sent and received. The helicopter adopts the mixed layout of local integrated cockpit. The use of the first generation night vision system enables helicopters to fly at night. This advanced semi-integrated electronic equipment significantly increases the communication distance, navigation distance and accuracy of the helicopter, reduces the number of instruments, reduces the workload of pilots, and enables the helicopter to fly on the ground and under bad weather/night conditions, thus improving the overall performance of the helicopter. The dynamic performance is obviously improved. The lift-to-drag ratio of the helicopter reaches 5.4, the vibration level of the whole helicopter is about 0. 1g, the noise level is lower than 95dB, and the maximum flight speed reaches 300 km/h ... The 1990s is the fourth stage of helicopter development, and an armed reconnaissance helicopter with stealth design integrating vision, acoustics, infrared and radar appears. Typical models are: American RAH-66 and S-92, international cooperation Tiger, NH90 and EH 10 1 etc. , known as the fourth generation helicopter. The helicopter at this stage has the following characteristics: it adopts the third generation turboshaft engine. Although this engine still adopts the free vortex shaft structure, it adopts the advanced digital control system and automatic monitoring system of the engine, and is integrated with the airborne computer management system, which has remarkable technical progress and comprehensive characteristics. The fuel consumption of the third generation turboshaft engine is only 0.28kg/kWh, which is lower than that of the piston engine. Its representative engines are T800, RTM322 and RTM390. The blade is made of advanced composite materials such as carbon fiber and Kevlar, and its life is infinite. There are many new blade tip shapes, among which BERP blade tips with parabolic swept back and forward swept back are more prominent. The common characteristics of these new blades are that they can weaken the compressibility effect of the blades, improve the aerodynamic load distribution of the blades, reduce the vibration and noise of the rotor and improve the aerodynamic efficiency of the rotor. Spherical flexible bearingless hub has been widely used. The hub shell and the blade connection part are made of composite materials, which makes the structure more compact and greatly reduces the weight and resistance. The lift-drag ratio of the rotor reaches 10.5, and the rotor efficiency is 0.8. At this stage, the tailless reaction torque system has the advantages of good control response characteristics, small vibration and low noise, and there is no need for tail transmission shaft and tail deceleration, which greatly reduces the number of parts, thus improving maintainability. Composite materials are widely used in helicopters as never before. Helicopters began to use composite main structures, and the application proportion of composite materials increased greatly, usually accounting for 30~50% of the weight of fuselage structure. During this period, the empty/total weight ratio of civil helicopters was about 0.37. Highly integrated electronic equipment. Computer technology, information technology and intelligent technology have been applied in helicopters, and helicopter electronic equipment is developing in a highly integrated direction. During this period, the helicopter has adopted advanced stabilization and control devices, replaced the conventional control system with telex and optical transmission control, adopted advanced strapdown inertial navigation, satellite navigation equipment and integrated navigation technology, advanced communication, identification and information transmission equipment, advanced fire control equipment such as target identification, aiming and weapon launch, advanced electronic countermeasures equipment, and adopted bus information transmission and data fusion technology, which are developing towards sensor fusion. The onboard electronics, fire control and flight control systems are connected through redundant digital data buses to realize information sharing. Adopt multifunctional integrated display technology. A small number of multifunctional displays are used to replace a large number of single instruments, and the flight information of helicopters is displayed through keyboard control. Information such as communication, navigation, flight control, friend-or-foe identification, electronic countermeasures, system monitoring and weapon fire control is integrated by the central computer. The use of this advanced integrated electronic equipment greatly simplifies the layout of the helicopter cockpit and instrument panel, simplifies the system components and greatly reduces the weight. More importantly, it greatly reduces the workload of pilots and improves the quality and performance of helicopters. The lift-drag ratio of the whole aircraft reaches 6.6, the vibration level is reduced to 0.05g, the noise level is less than 90 dB, and the maximum speed can reach 350 km/h. As a means of transportation, the helicopter is the only flight platform that can reach any terrain area. As a working tool, it is widely used in industrial, agricultural and commercial activities, and plays an irreplaceable role in medical rescue, emergency rescue and disaster relief, hoisting, forest fire fighting, public security patrol and other fields. As a means of transportation, helicopter is the only flight platform that can reach any terrain area; As a working tool, it is widely used in industrial, agricultural and commercial activities, and plays an irreplaceable role in medical rescue, emergency rescue and disaster relief, hoisting, forest fire fighting, public security patrol and other fields. According to statistics, there are currently more than 20,000 private and civilian helicopters in the world, and the number of helicopters owned and used has become one of the important indicators to measure a country's technological and economic level. According to statistics, there are currently more than 20,000 private and civilian helicopters in the world, and the number of helicopters owned and used has become one of the important indicators to measure a country's technological and economic level.